RAPID: Hurricane Impact on Phytoplankton Community Dynamics and Metabolic Response

飓风哈维是几十年来袭击德克萨斯州海岸的最强飓风，由此产生的潮汐、洪水和陆地径流对沿海海洋造成了严重影响。作为食物链的第一环，浮游植物受到的影响可能是前所未有的。为了确定浮游植物群落将如何应对盐度、养分输入和潜在毒素的剧烈变化，立即和连续取样是充分捕捉影响并确定条件何时恢复“正常”的唯一方法。部署在德克萨斯海岸的一种自动的、连续的浮游植物成像仪器记录了浮游植物的图像，并允许计算不同种类的丰度。与已“开启”或表达的基因分子信息一起，这个项目的结果将有助于确定个别类型浮游植物的反应。随着未来的气候变化，极端风暴的频率预计会增加，因此，现在确定的响应对于预测这些事件将如何影响这些初级生产者是有价值的，而这些初级生产者反过来又支持海洋生态系统中的大多数食物网。影像流式细胞机器人（IFCB）的高时间分辨率观测显示，墨西哥湾的飓风引起了浮游植物群落结构的剧烈变化。这个RAPID项目的目标是：1)描述浮游植物物种与德克萨斯州海岸环境变量相关的动态特征；2)评估浮游植物群落的短期和长期变化；3)确定浮游植物群落的资源获取策略。为了实现这些目标，本项目将利用IFCB时间序列来跟踪飓风哈维后恢复期的浮游植物群落结构。此外，两次快速反应巡航（9月底和10月初）沿着加尔维斯顿到阿兰萨斯港的样带在德克萨斯州的5个地点取样。在每个站点，CTD剖面和水面水样以及叶绿素最大值将被收集，用于营养物质，碳酸盐化学和RNA测序，用于亚转录组学分析。元转录组学可以提供浮游生物群落在响应环境变化时所采用的代谢策略和功能关系的指示。亚转录组学方法的优点是捕获对环境的整个分子反应。因此，虽然浮游植物对洪水径流增加的营养输入的反应是有针对性的，但对其他环境压力（有毒物质、缺氧、酸化）的反应也被捕获。利用多元统计技术对这一时间序列进行分析，如主成分分析（PCA）和网络分析（一种识别分类群之间潜在相互作用的强大技术），将为飓风过后构建群落的环境因素和代谢反应提供见解。

Hurricane Harvey is the strongest hurricane to hit the Texas coast in decades and the resulting tidal surges, flooding and terrestrial runoff have had a severe impact on the coastal ocean. The effects on the phytoplankton, the first link in the food chain, may be unprecedented. To determine how the phytoplankton community will respond to such drastic changes in salinity, nutrient inputs, and potential toxins, immediate and continuous sampling is the only way to fully capture the effects and to identify when conditions return to "normal". An automated, continuous phytoplankton imaging instrument that is deployed on the Texas coast records images of the phytoplankton and permits calculation of the abundance of different species. Together with molecular information on the genes that have been "turned on", or expressed, outcomes of this project will help determine the responses of individual types of phytoplankton. Extreme storms are expected to increase in frequency with future climate change, so the responses identified now will be valuable in predicting how such events will affect these primary producers, which in turn support most of the food webs in marine ecosystems, in the future.High temporal resolution observations from the Imaging FlowCytobot (IFCB) have revealed that hurricanes in the Gulf of Mexico cause drastic changes in the phytoplankton community structure. The objectives of this RAPID project are: 1) to characterize the dynamics of the phytoplankton species in relation to the environmental variables along the Texas coast; 2) to assess the short and long-term changes in the phytoplankton community; and 3) to identify the strategies of the phytoplankton community for resource acquisition. To accomplish these objectives, this project will utilize IFCB time series to follow phytoplankton community structure during the recovery period from Hurricane Harvey. In addition, two RAPID response cruises (in late September and early October) to sample at 5 sites along a transect from Galveston to Port Aransas, TX. At each station, CTD profiles and water samples from surface and the chlorophyll maximum will be collected for nutrients, carbonate chemistry, and RNA sequencing for metatranscriptomic analysis. Metatranscriptomics can provide an indication of the metabolic strategies employed and functional relationships within the plankton community in response to changes in the environment. The advantage of a metatranscriptomic approach is that the entire molecular response to the environment is captured. So, while the response of phytoplankton to increased nutrient inputs from floodwater runoff is targeted, the responses to other environmental stresses (toxics, hypoxia, acidification) are also captured. Analyses of this time series using multivariate statistical techniques, such as principal component analysis (PCA), and network analysis, a powerful technique for identifying potential interactions among taxa, will provide insights on the environmental factors and metabolic responses structuring the community during the aftermath of the hurricane.